Telephone switching apparatus.



B. D. WiLLISI TELEPHONE SWH'CHJNG APPARATUS APPLICATION FILED MAR. 27, IBM.

Patented Apr. 6, 1915.

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TELEPHONE SWiTCHING APPARAYUS. APPLlCATION FILED MAR. 21. l9i!.

Patented Apr. 6, 1915.

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UNITED STATES PATENT OFFICE.

BERNARD D. WILLIS, OF CHICAGO, ILLINOIS, ASSIGNOB T0 AUTOMATIC ELECTRIC COHYANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

Specification of Letters rctcnt.

Patented Apr. 6, 1915.

Application filed March 27. 1911. Serial H0. 617,027.

To all whom it may concern Be it known that I, Bnnxann D. WILLIS, a citizen of the United States of America, and resident of Chicago, Cook county, IlliIlOlS, have invented a certain new and, useful Improvement in Telephone Switching Apparatus, of which the following is a specification.

My invention relates to telephone systems in general, but more particularly to systems employing automatic switches, and especially to semi-automatic systems.

Generally stated, the object of my invention is to provide an improved construction and circuit arrangement for automatically extending connection from a calling telephone line.

A special object is to provide an improved system of thiskind in which the said connection from the calling line is established through the medium ofa switch that, when idle or not in use for talking purposes, is always iii-motion and'thus constantly searching for a callingrline, and in which provision is made for automatically stopping the said switch as soon as it finds a calling line, whereby the cord and plug that is allotted to the said switch is automatically placed in connection with the line, the said cord having a signal by whic the fact that a subscriber is calling 0 rator at whose position the said cord and p ng are located, thus simplifying the appgliiatus and the method of extending t e c Another object is. to provide a system of this kind in which there are a plurality of said automatic finder switches, with a cord and plug or other suitable connection for each switch, and in which a master switch or other suitable mechanism is provided for sucmsively controlling the said switches, whereby only one finder switch at a time is operative to automatically stop on a calling line, the said master switch serving automatically to select another finder switch each time a switch of this kind is stopped and temporarily appropriated for use by a calling subscriber in extending the call.

It is also anobject to provide certain details and features of improvement and novel combinations tending to increasethe general 'eflicicncy and serviceability of a telephone Lexch system of this particular character. To t e foregoing and other usefiil ends,

is indicated to the my invention consists in matters hereinafter set forth and claimed.

In the accompanying drawings, Figure 1 shows detail a side elevation of my imroved finder switch. Fig. 2 is a view showmg the lower side of one of the electromagnets shown in Fig. 1. Fig. 3 represents diagrammatically a complete circuit connection established. between a calling manual substation A and it called manual substation A in a system embodying the principles of my invention.

The apparatus shown in Fig. 1 comprises what will be herein known as a finder switch It consists essentially of three operating magnets 2, 3 and 4, mounted upon the frame 8, and their respective armatures ,5, 6 and 7. Referring to Fig. 2, it will be seen that the end ofthe cores'of each of the magnets is made to form an arc of a circle, thus allowing the armature! to be attracted directly toward that portion of the core in front of which it may be standing when the magnet 4 is energized. For convenience, only one of the magnets (the magnet 4, for example), with its corresponding armature, will be described, it being understood that the remaining ones are constructed and mounted in a manner similar to the one described. The armature! which is to be attracted by the magnet 4 is securely fastened to the outer end of the pin 9, which is loosely mounted inthe uprights 10 and 11 on the end of the arm 12, and is normally held away from the core '13 of the magnet 4 due to the tension of the coil'spring 14. The pin 9 is adapted, when in the proper position, to engage the opening 15 in the shaft 16. The arm 12 is loosely mounted upon the shaft 16. The outer end of the arm 12 carries a wiper 17 adapted to pass over a row of contacts a. The inner end, besides carrying the armature 7, also carries a wiper 18 which is adapted to engage the circular contact 19, which is mounted on the electromagnet 4, The shaft 16 is given a reciprocating motion by some external source of power, so that when the pin 9 engages the opening 15 in the shaft 16 the wiper 17 is moved back and forth over the row of contacts a. The wiper 18 is also moved back and forth, but is not moved out of engap'gment with. the contact 19. The wipers 17 and 13 are connected with each other by means of a wire; Thus it will be seen that when the electromagnet 4 is energized, it operates against the tension of the spring 14 to move the pin 9 from the opening in the shaft 16, thus allowing the arm 12 to remain in an energized position, with the wiper I? resting on one of the contacts of the group of contacts a.

The manual substation shownin Fig. 3 may be of any suitable or-approved type. The one shown at A, for example, compr ses the usual receiver 20, transmitter 21, bells 22 and condenser :23.

The organization of the system as shown herein is as follows: The subscribers lines are divided into groups. The lines of each group are connected to the bank contacts of a plurality of finder switches, the rotating arms ofwhich are mounted upon a common shaft-that is, for each group of lines there is a group of finder switches less 1n number than the number of lines in the group. In Fig. 3 there are shown three switches .C, C' and Cof a group, together with a portion of their bank contacts. The bank contacts are shown rotated through an angle of ninety degrees from their-true position, so as to indicate more clearly the'manner 1n which'the lines are connected thereto. To each finder switch there is 'alloted an operator's cord D terminating in a plug P. The subscribers lines are also provided with multiple jacks, as shown at J and J.

At E a so-called master switch is shown which is common to the group of cords of which the cord 1) is a member. The master switch E,-through the medium of the wipers 24-, '25, 26 and 27 and banks 6 and 6, controls the circuits of the double-wound relays 26, 29 and 30 which are individual to the finder switches C, C and C respectively.

The master switch consists essentially of the motor magnet 31 for controlling the ratchet wheel 32, which is securely mounted upon the same shaft with the wipers 24 and 25, and 26 ml 27. The master'switch also comprises the two circuit-controlling relays 33 and 3 The stop magnet 35 operates to disconnectthe clutch 36 from its intermeshing clutch 37. When the magnet 35 is energized,the clutch 36 djsengages the clutch 37, thereby allowing the shaft upon which the wipers of the finder switches are mounted to remain stationary.

At B battery is shown with its positive terminal preferably grounded'at G. At S an operators talkingset is'shown.

Having'given a general description of the apparatus in the foregoing invention, I will now describe the operations brought about when the subscriber at one substation .51 and makes connection with another subscriber, the subscriber at substation A, for example. i

magma The subscriber at substation A, upon removing the recciver from the hook, connects the two sides of his line together through the talking bridge. As soon thereafter as the wipers of the finder switches pass over the bank terminals of his line, a circuit is closed through the double-wound relay '28, which is individual to the finder switch C that is, assuming that the wipers :24, :25, 26 and 27 are resting upon the contacts of a trunk line leading to the double-wound relay 28. This circuit through the doublewound relay 28 extends from ground G through the left-hand winding of the relay 34, armature 38, contact 39, wiper 27, bank contact 40, lower winding of the relay 28, contact 41, wiper 42, wiper 43, contact 44, line conductor 45, switch hook 46, contact 47, receiver 20, transmitter 21, line conductor 48, contact l9, wiper 50, wi er 51, contact 52, upper winding of the re ay 28, master switch bank contact 53, wiper 26, contact 54, armature 55, thence through the righthand winding of the relay 3% to the battery lead 56, and through battery B to ground G. The relay 28 energizes upon the closure of this circuit and closes a circuit through the two line magnets and private magnet of the finder switch C, This circuit extends from ground Gr through the line magnet 57, line magnet 58, private magnet 59, contact point 60, armature 61 tothe battery lead 56, thence through battery B to ground G. 'At the same time the relay 34 operates to close a circuit from ground G through the contact 82, armature 83 and stop magnet 35 to the battery lead 56. The magnet 35, upon energizing, disconnects the driving power from the shaft 84, 'allowingit to momentarily come to rest, while at the same time the magnets 57, 58 and 59 operate to withdraw the pins 85, S6 and 87 from their respective openings in the shaft 84, thereby disconnectin the arms 50, 43 and 77 there from and a owing them to come to rest upon the contacts of the line A. The energization of the relay 28 also closes an energizing circuit through the doubleavound relay 62. This circuit extends from ground G through the lower winding of the relay 62, contact point 60, armature 61 to the battery lead 56. The energization of the relay closes an energizing circuit through the line relays 63 and 64 of the cord circuit D. This circuit extendsfrom ground G through the relay 64, contact point 65, armature thence over the circuit previously traced to and through the substation A, back over the circuit previously traced to the point 67, thencethrough the armature 1 68, contact point 69, line relay 63 to the battery lead 56, The relay 6%, upon energizing, closes the circuit extending from ground G through the armature 70, contact point 71, conductor 72'to the point 73. One

branch leads from the point 73 over the conductor ?4, contact 75, wiper 76 and wiper 77 to the private contacts of the calling line in the bank of all finder switches which have access to the calling line. Another branch leads from the point 73 through the wiper 25, cutoff relay 33 to the batterylead 56. The energization of the relay 64 also closes the circuit extending from ground G through the armature 78,-"contact point 79, master switch bank contact 80, wiper 24, motor magnet 31, interrupter springs 81 to the battery lead 56. The motor magnet 31, upon energizin", operates to rotate the ratchet wheel 32 one step. The rotation of the ratchet wheel one step moves the wipers 24, 25, 26 and 27 out of engagement with the contacts upon which they were standing and into engagement with the next succeeding contacts, which, as before explained, are terminals of lines leading to a doublewound relay similar to those'shown at 28, 29 and 30. Sincethe circuit of the motor magnet 31 includes the interrupter springs 81, the motor magnet, upon energizing, breaks its own circuit. Therefore, as soon as the shaft is rotated one step the armature 82 returns to normal'position, which again supplies battery current to the motor magnet 31. Assuming that the contacts upon which the wipers 24, 25, 26' and 27 are rotated are idle, the motor magnet 31 will remain denergized. If, however, the contacts upon which the said wipers are rotated are busy, the wipers 24 and 25 will find the corresponding contacts grounded, thereby again closing a circuit through the relays 33 and 31, which will again operate to rotate the ratchet wheel 32 another step. Thus it will be seen that as long as the wipers 24 and 25 come in contact with grounded bank contacts, the master switch will continue to operate.

The energizationof the relay 33, mentioned above, opens the circuit of the relay 34, which dee'nergizes and breaks the circuit of the stop magnet 35. Thus'it will be seen that the energization of the stop magnet 35 is only momentary, long enough, however, to allow the pins 85, 86 and 87 to be withdrawn from the shaft, 8-1. After'the master switch has operated, the circuitof the relay 3% is broken at the wipers 26, and 27. Consequently, the relay 35 remains deiinergized 5 and the shaft continues to operate to carry the Wipei'sof the idlefinder switch over their bank contacts. Should it desired for any reason to permanently stop the shaft 84. the key K is thrown,; thus closing the circuit from ground Gt through the key K and the magnet 35 to battery. Before the circuit of the relay 28 isbi'oken hytlie rotation of the master switch 26 and a new circuit is completedthrough the magnets 57, 5s and'59 and the upper winding of the relay 62 in series. This circuit is closed upon the energization of the relay 63 and extends from ground G through the magnets 57, 5S and 59. upper winding of the relay 62, contact 88 and armature 89 to the battery lead 56. It will be seen that the lower winding of the relay 62 is in multiple with the magnets 57, 5S and 59. The magnets 57, 58 and 59, as well as the relay 62, remain energ'zed over the circuit just traced. and operate to hold the pins 85, S6 and 87 out of engagement with the shaft 84. Thus the wipers 50, 43 and T7 are allowed to remain stationary upon their corresponding contacts. The energization of the relay 63 also closes a circuit through the lamp 90. This circuit extends from ground G through the armature 91, contact point 92, lamp 90, contact point 93 and armature 89 to the battery lead 56. The glowing of the lamp 90 signifies to the operator that a calling party desires a connection. Upon seeing the lamp 90 lighted the operator operates the key K to connect her talking set S with the lines of the calling station. Upon learning the number desired she inserts the plug P into the jack J. The insertion of the plug P into the jack J completes the connection between the calling substation A and the called substation A. The insertion of the plug P into the jack J also closes an energizing circuit through the relay 94. This circuit extends from ground G through the relay 94, sleeve of the plug P and jack J and resistance 95 to the battery lead 56. A circuit also extends from the sleeve of the jack J over the conductor 96 to the private bank contacts of the called line in the banks of all the finder switches which has access to said line. The relay 94 energizes in series with the resistance 95 and supplies a new holding circuit for the relay 62 by the closure of the contacts 97 and 98. The engagement of the springs 99 and 100 supplies ground to the lamp 101. The engagement of the springs 102 and 103 supplies a new guarding ground to the private bank contacts of the calling line. After inserting the plug P into the jack J, the operator throws the key K in the proper direction to shift the springs 10% and 105 out of engagement with the springs 106 and 107 and into engagement with the springs 108 and 109, respectively. The disengagement of the springs 104 and 106, and 105 and 107 disconnects the calling line from the plug P. The engagement of the springs 10.4: and 108. and 105 and 109 closes a ringing current from the generator R onto the line of the called subscriber. After ringing thecalled subscriber the operator again places the key K in normal position. which allows the two substations to be againconnected. The called subscriber. upon hearing the call signal, removes the receiver from the'hooln The removal of the'receiver from the hook at the called station closes the circuit through the double-wound relay 110. This circuit extends from ground G through the lower winding of the relay 110, ring of the plug P and jack J, line conductor 111, switch hook 112, contact 113, receiver 114, transmitter 115, line conductor 116, tip of the jack J, plug P and upper winding of the relay 110 to the battery lead 56. The relay 110 energizes over the circuit just traced to disconnect ground from the lamp 90 by the disengagement of the springs 91 and 92. The called subscriber receives talking battery current over the circuit just traced, while the calling subscriber receives talking battery current through the line relays 63 and 64. The calling and called subscribers may now carry on an uninterrupted conversation over the connection as completed. The hanging up of the receiver at the called substation allows the relay 110 to deia'nergize, which again closes the circuit of the lamp 90. The hanging up of the reoeiver at the calling substation breaks the circuit of the line relays 63 and 64. The relay 63, upon denergizing, closes the circuit of the lamp 101, the relay 94 being in an energized position. The battery is supplied to the lamp 90 after the denergization of the relay 63 from the spring 117 on the relay 94. Thus it will beseenthatthehanging up of the receiver at the calling and called substations causes the lamps 90 and 101 to glow, which signifies to the operator that the connection 1s ready to be taken down. The operator thereupon removes the plug P from the jack J, which causes the deenergization of the relay 94. The relay 94, upon denergizing, opens the circuit of the lamps 90 and 101, removes the guarding ground from the private bank contacts of the calling line and breaks the circuit of the relay 62 and magnets 57 58 and 59. The deenergization of the relay 62 disconnects the finder switch from the cord. The denergization of the magnets 57, 58 and 59 allows the pins 85, S6 and 87 to again return into engagement with the shaft 84. Had the called line been busy the operator would have received a click by tapping the tip of the plug onto the sleeve of the jack in the usual manner.

In the foregoing description it has been explained that when two lines are connected the contacts of both lines in the private or test banks of the finder switches are pro vided with a ground potential. This is .to prevent the finder switches from stopping on busy lines. This is accomplished as follows: Suppose that while the wipers of the master switch are resting on the contacts belonging to the switch 0, the iwipers of the switchm engage the contacts of a busy line. guarded contact of said line the guarding 4* th th esa the masse ground potential is extended over the conductor T4, wiper 25 and through the cut-0E relay 33 to battery. The relay 33 energizes and opens the connection between the relays 28 and 34, thus preventing them from energizing and causing the switch C to connect with the busy line. In order to accomplish this result the wiper 77 may be arranged to close the circuit of the relay 33 an instant before the line wipers 43 and 50 engage their contacts.

Thus it will be seen that I provide an improved semi-antomatic telephone exchange system in which constantly operating finder switches are provided and in which the telephone lines have multiple contacts over which the switches,'when idle or not in use for talking purposes, are always moving in a search for calling lines. In sense, therefore, the idle cords and plugs which are individual to these switches are always looking for calling telephone lines-that is to say, whenever-'11 cord and plulgnis idle it is, through the medium of its der switch, constantly searching for a calling telephone line. Each cord consists of a pair of voicecurrent conductors, and for each pair of conductors there is a battery bridge, the bridges of the diflferent finder switches being successively controlled by the master switch. In this way only one finder switch at a time is in condition to automatically stop on a calling line. The master switch immediately selects another finder switch whenever the particular findersw'itch that was waiting for a call is stopped and temporarily appropriated by a calling subscriber for extending the Thus the stopping circuit of only one finder switch at same is closed, the others being open, whereby the finder switches are successively brought into condition to pick up the next call. In this way the apparatus and the method of are much simplified.

What I'claim as my invention is:

1. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, devices for keeping said switches in motion, magnets for automaticall stopping a switch on a calling line, n ec anism for controlling said switches, and a pair of voice-current conductors for each switch adapted to be connected to calling lines by the said switches, said mechanism comprising a master switch operative to automatically select another finder switch each time a switch is taken by a calling subscriber.

2. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, devices for keeping said switches in motion, magnets for automatically stopping a switch on a calling line, mechanism for controlling said switches, and a pair of voice-current conductols for each switch adapted to be connected to calling lines by the said switches, said mechanism comprising a master switch whereby only one switch at a time is in condition to stop on a calling line.

3. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, devices for keeping said switches in motion, magnets for automatically stopping a switch on a calling line, mechanism for controlling said switches, a air of voice'current conductors for each switch adapted to: be connected to calling lines by the said switches, a battery bridgefor each pair of conductors, which bridges are successively closed by said mechanism, and relays in said bridges for controlling said magnets. v

4. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, devices for keeping said switches in, motion, magnets for automatically stopping a switch on a calling line, mechanism .for controlling said switches, a pair of voice-current conductors for each switch adapted to be connected to calling lines by the said switches, a battery bridge for ,each pair of conductors, which bridges are successively closed by said mechanism, and relays in said bridges for controlling said magnets, the battery of said bridges supplying current to calling lines for talking purposes. v

5. In a telephone symm, telephone lines, a plurality of finder switches in which said lines have multiple contacts, devices for keeping said switches in motion, magnets for automatically stopping a switch on a calling line, mechanism for controlling said switches, a pair of voice-current conductors for each switch adapted to be connected to calling lines by the said switches, multiple jacks for said lines, and cord plugs for said conductors, which plugs are insertible in multi 1e jacks of called lines.

6. iii a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, normal connections between the said lines and said contacts, devices for keeping said switches in motion, magnets for automatically stopping a switch on a calling line, mechanism for controlling said switches, a pair of voicecurrent conductors for each switch adapted to be rubbed over the contacts of successive calling lines and be connected to one of said lines by the said switches, condensers in said conductors, and battery bridges at opposite sides of said condensers for supplying talking current to calling and called lines.

7. In a telephone system, telephone lines,a plurality of tinder switches in which said lines have multiple contacts, devices for keeping said switches in motion, magnets for automatically stopping a switch on a calling line, mechanism for controlling said switches, a pair of voice-current conductors for each switch adapted to be connected to calling lines by the said switches, and a battery bridge for each pair of conductors, said bridges being successively controlled by said mechanism.

8. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, devices for moving said switches over said contacts, magnets for automatically stopping a switch on a calling line, a pair of voice-current conductors for each switch adapted to be connected with calling lines by said switches, and means for preventing said switches from stopping on a. line which is in use, a common driver and means for stopping said driver each time a connection is extended.

9. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, and a master switch for controlling the operation of said finder switches to bring said switches successively into operation to connect with a calling line in response to a plurality of successive calls.

10. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, each of said finder switches comprising an operating magnet having an arc-shapedpole-piece, a pivoted arm carrying an armature. mounted adjacent said pole-piece and carrying a contact adapted'to pass over said multiple contacts, means for oscillating. said arm, and means for stopping said arm by energizing said magnet to connect said switch with one oi said lines.

11. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, each of said finder switches comprising an operating magnet, a pivoted arm carrying an armature mounted adjacent said magnet, means for oscillating said arm, said arm carrying a contact adapted to rub over said multiple contacts during said oscillation, means for stopping said arm by energizing said magnet to establish a circuit for talking with one of said lines, said circuit including said contact and one of said multiple contacts, and a master switch for successively bringing a plurality of said switches into operation.

12. In a telephone system, telephone lines, a pluralty of finder switches in which said lines have multiple contacts, each of said switches comprising an operating magnet, an arm having an armature mounted adjacent the pole-piece of said magnet, an oscillating shaft carrying said arm, a contact carried by said arm adapted to engage with said multiple contacts, and means for ener- 'izing said magnet to disconnect said arm Irom said shaft to connect said switch with one of said lines.

13. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, each of said switches comprising an operating magnet, an arm having an armature mounted adja' cent the pole-piece of said magnet, an oscillating shaft carrying said arm, a contact carried by said arm adapted to engage with said multiple contacts, means for energizing said magnet to disconnect said arm from said shaft to connect said switch with one of said lines, and a master switch for successively bringing a plurality of said switches into operation.

14. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, each of said finder switches comprising an operating magnet and a pivote arm carrying wipers adapted to rub over said multiple contacts and adapted to be included in a talking circuit, a master switch with which sai wipers are adapted to be operatively connected, and means for disconnecting said wipers from said master switch.

15. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, each of said finder switches comprising an operating magnet, a pivoted arm carrying an armature mounted adjacent said magnet and carrying a wiper adapted to rub over said multiple contacts and adapted to be included in a talking circuit, a master switch tapes with which said wipers are adapted to be operatively connected, means controlled by said master switch for oscillating said wipers, and means controlled by said operating magnet for disconnecting the corresponding wiper from the master switch.

16. In a telephone system, lines, terminals for said lines, switches for connecting with said lines via said terminals, automatic means for maintaining each switch in motion while no switching operations are occurring, a magnet for each one of said switches and an automatic common device for controlling the circuits of said magnets to brin their corresponding switches into use or connecting with the said lines if idle.

17. In a telephone system, telephone lines, a plurality of finder switches in which said lines have multiple contacts, each of said finder switches comprising an operating magnet having an arc-shaped pole-piece, a pivoted arm carrying an armature mounted adjacent said pole-piece and carrying a contact adapted to pass over said multiple contacts, means for oscillating said arm, means for stopping said am by energizing said ma et to connect s'aid switch with one of sai lines, and a master switch for preselecting the next finder switch to he brought into operation.

Signed by me at Chica 6, Cook county Illinois, this 16th day of birch, 1911.

BERNARD D. WILLIS.

Witnesses:

ARTHUR J. RAY, E. D. Fates.

copies of this patent may be obtained for he cents each, by addressing the commissioner of Patents.

Washington, D. C.

It is hereby certified that in Letters Patent No. 1,134,933, granted April 6, 1915, open the npplicatioh of Bernard D. Willis, of Chicago, Illinois, for an improvemel it in Telephone Svihfehihg Apparatus, errors appear in the printed specification reqhiring correction f le How s," Page 3, line 104, for the word has read page 4, lines 64 and 65 should be transposed; and that the 'aaid Letters Patent should be read with these corrections therein that the same may confoim to the record of the case in the Patent Oflice.

Signed and sealed this 25th day of May, A. D., 1915.

R. F WHITEHEAD,

Acting C'ommunon' erofiPatok [emu] 

